Pump assembly

ABSTRACT

A pump assembly includes an electrical drive motor, at least one impeller ( 14 ) which is rotatingly driven by the electrical drive motor as well as a control device ( 17 ) which activates the drive motor. The control device ( 17 ) is configured such that the control device ( 17 ) selectively activates the drive motor in at least one first or a second operating mode. In a first operating mode, the drive motor is activated by the control device ( 17 ) such that a rotor ( 6 ) of the drive motor continuously rotates. In the second operating mode the drive motor is controlled by the control device ( 17 ) such that the rotor ( 6 ) of the drive motor is moved further stepwise manner in at least one selected angular step of preferably smaller than 360°.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a United States National Phase Application of International Application PCT/EP2018/056080, filed Mar. 12, 2018, and claims the benefit of priority under 35 U.S.C. § 119 of European Application 17 160 832.6, filed Mar. 14, 2017, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a pump assembly with an electrical drive motor, with at least one impeller which is rotatingly driven by the electrical drive motor as well as with a control device which activates the drive motor.

TECHNICAL BACKGROUND

In modern pump assemblies, it is known to activate (control) the drive motor via a control device with a frequency converter, so that the drive motor can be adjusted and regulated in its speed. However, the speed range, over which the speed can be changed, is limited.

SUMMARY

It is the object of the invention to improve a pump assembly with an electrical drive motor, to the extent that the drive motor can be set or driven over a larger speed range.

The pump assembly according to the invention comprises an electrical drive motor as well as at least one impeller which is rotatingly driven by this. For this, the impeller can be connected to the rotor of the drive motor in the known manner. The rotor is particularly preferably a permanent magnet motor. Further preferably, the drive motor is configured as a wet-running electrical drive motor with a can or canned pot which separates the rotor space from the stator space. This means that the rotor preferably rotates in the fluid which is to be delivered by the pump assembly. The pump assembly can preferably be configured as a circulation pump assembly and further preferably as a heating circulation pump assembly.

According to the invention, the control device of the drive motor which activates the drive motor and in particular controls the current-subjection of stator coils in the stator of the drive motor is configured in a manner such that it selectively activates the drive motor in at least one first or in a second operating mode. Here, the first operating mode is a conventional operating mode, with regard to which the drive motor is activated by the control device in a manner such that the rotor of the drive motor continuously rotates over a multitude of revolutions. In this operating mode, the impeller is driven such that it produces the pressure and the flow which are desired for the operation of the pump assembly. In contrast, in the second operating mode, the control device activates the drive motor such that the rotor of the drive motor is only moved further in a stepwise manner in at least one selected, in particular adjustable angular step, wherein these angular steps are preferably smaller than 360 degrees. This rotation in at least one selected angular step serves for rotating the rotor into a desired angular position. This permits the drive motor, in the second operating mode, to be able to assume further drive functions and in particular actuating functions, as could be otherwise be assumed by stepper motors. This permits further fields of application. The drive motor in the pump assembly, apart from the drive of the impeller, can therefore assume further functions, in particular actuating functions for moving further components which only need to be moved over smaller paths.

The control device is preferably configured such that in the first operating mode, the drive motor rotates at a higher angular speed than in the second operating mode. This is advantageous for drive functions and actuating functions, in which smaller movements are to be carried out with a greater accuracy.

The control device is preferably configured such that in the first operating mode, the drive motor is adjustable and in particular can be closed-loop controlled (regulated) in its speed. For this, the drive motor in its control device can preferably comprise a frequency converter, via which the speed of the drive motor can be changed.

The control device is further preferably configured such that in the second operating mode, the drive motor is controlled by the control device with an open loop, which is to say is in open-loop operation, in which no closed-loop control of the position is carried out on subjecting the stator coils to current. In particular, the back-EMF is not used in the control or regulation (closed-loop control) on open-loop operation. This control permits the drive motor to be rotated by certain angles in targeted manner by way of subjecting the coils in the stator to current accordingly. In the known manner, the stator can be provided with a plurality of stator poles and associated stator coils which are configured for example for three-phase operation.

According to a further preferred embodiment, the control device is configured in a manner such that in the second operating mode, the drive motor is activated by the control device at a frequency <10 Hertz. This means that the stator coils are subjected to voltage or current at a frequency <10 Hertz. Alternatively or additionally, a motor current which is greater than in the first operating mode is used. In the operating mode, one can therefore use a motor current or the stator coils can be subjected to a current, said current corresponding to twice to fourfold the rated amperage, for which the drive motor is configured. The amperage can possibly also be greater than fourfold the rated amperage which is to say the rated current strength. It is essentially only limited by the fact that a demagnetization of the rotor should not be allowed to occur.

According to a further preferred embodiment, the control device is configured in a manner such that the number and/or the magnitude of the individual angular steps, with which the rotor is moved in the second operating mode, are selectable. It is therefore possible to rotate the rotor into the desired angular position in a targeted manner. For this, the control device subjects the individual stator coils to current in a targeted manner.

Further preferably, the control device can be configured such that it activates the drive motor such that its rotation direction in the second operating mode is opposite to the rotation direction in the first operating mode. This simplifies the use of the different operating modes for different applications, since apart from the impeller, for example further components could be coupled to the rotor via a rotation-direction-dependent coupling, so that in one rotation direction only the rotor is driven, whereas in the other rotation direction which is preferably used in the second operating mode, yet a further coupled component could be moved.

The pump assembly therefore preferably has a further movable component which additionally to the at least one rotor is coupled to the rotor of the drive motor via a releasable coupling. Here, the coupling can engage directly on the rotor, on a rotor shaft which is connected to the rotor or also on the impeller which is arranged on the rotor shaft in a rotationally fixed manner. The at least one further movable component can for example be a valve element, wherein the valve element is preferably part of a mixing and/or switch-over valve. Such a switch-over valve can for example be a switch-over valve which is used in a heating facility, in order to switch the flow path between a heating circuit and a service water heat exchanger. A mixing valve for example can be a mixing valve as is applied in a heating facility, in order to regulate the feed temperature by way of admixing cooled heating medium.

The described coupling for the coupling of the at least one further movable component is preferably releasable in a rotation-direction-dependent manner, which is to say a manner which is dependent on the rotation direction, so that in one rotation direction the additional component can be moved in the described manner, whereas in the opposite rotation direction which is preferably used in the first operating mode, the impeller can rotate in normal operation and perform a pumping function without being compromised. The impeller can comprise blades which are adapted to this rotation direction which is preferred for normal operation.

The mentioned coupling can further preferably be formed on a face end of the rotor shaft of the rotor. The component which is to be moved then comprises a corresponding counter-coupling which can come into engagement with this coupling. Here, the additional, movable component is preferably likewise rotatable and further preferably is rotatable about the same axis as the rotor shaft. The coupling at the face end of the rotor shaft in particular can comprise a saw-tooth profile, which is to say can comprise saw-tooth profile when unwound in the circumferential direction. This profile preferably comprises two inclinations, whose axially projecting face edges extend along a diameter line transversely to the rotation axis of the rotor shaft. Engagement surfaces which extend in a plane parallel to the rotation axis and to the diameter of the rotor shaft are therefore created preferably in a manner departing from these face edges. The inclinations or wedge surfaces can preferably extend away from these engagement surfaces in a manner departing from the face edges of the profile and in the opposite rotation direction they have the effect of the coupling being pressed out of engagement. This disengagement is then effected by way of an axial displacement of the counter-coupling and/or coupling on the rotor shaft.

According to a particularly preferred embodiment, the component which is to be additionally rotatingly moved is a valve element which is configured and arranged in a manner such that it is rotatingly movable between at least two switching positions. Here, the rotation axis of the valve element is preferably aligned to the rotation axis of the drive motor. This permits a simple construction of the described coupling. The valve element is preferably additionally axially displaceable along its rotation axis, wherein a coupling as has been described above can be brought out of engagement by way of the axial displacement of the valve element.

According to a further preferred embodiment, the valve element is arranged in the pump casing in a manner such that it comprises a pressure surface, upon which a pressure prevailing at the outlet side of the at least one impeller acts. This means that the pressure surface is preferably adjacent to the delivery chamber, in which the impeller rotates. The valve element is further preferably movably mounted in a direction transverse to the pressure surface, between a bearing position (contacting position), in which it bears on at least one contact surface (bearing surface), and a released position, in which it is released or distanced from the contact surface. The movement path, along which the valve element is movable between the adjacent position and the released position, here preferably differs from the movement path between the at least two switching positions of the valve element. Particularly preferably, the valve element is axially movable along the rotation axis, about which it is movable between the switching positions.

Further preferably, a restoring element or a biasing element is present, and this produces a restoring force which is directed oppositely to the pressing force which is produced by the pressure upon the pressure surface. Such a restoring element can for example be a spring. The restoring element is preferably arranged such that the produced restoring force presses the valve element into the released position. In the released position, the valve element is preferably essentially freely movable and in particular rotatable, so that it can be easily moved between its switching positions. In contrast, in the bearing position, the valve element is preferably non-positively and/or positively held on the contact surface, so that it is held in its assumed switching position.

At the same time, the at least one contact surface can preferably be a sealing surface. In this manner, the valve element is simultaneously sealed in the desired switching position, wherein the sealing surface preferably surrounds an inlet opening or switching opening and functions as a valve seat.

The pump assembly according to the invention permits the drive motor to be activated or controlled according to a new type of method which is likewise the subject-matter of the invention. Here, the essential method features are to be derived from the preceding description of the function of the pump assembly. The second operating mode is preferably utilized to move an additional component, in particular a valve element, into a desired position, in particular into a desired angular position with respect to a rotation axis. For this, the open-loop operation is utilized on activating the drive motor. At the same time, a rotation-direction-dependent coupling as has been described beforehand is provided preferably between the rotor and the rotatable valve element. The coupling is configured such that it engages in at least one angular position, and with the embodiment which has been described above, in two angular positions which are offset by 180. Since, in normal operation in the first operating mode, the coupling is disengaged in the manner described above due to the pressure prevailing in the delivery chamber, on changing into the second operating mode, it is not ensured that the valve element has not slight displaced. Inasmuch as this is concerned, on starting the second operating mode, it is preferable for the drive motor not to be rotated precisely in the angular position, in which it was located on last completion of the second operating mode, but for it to move into an angular position which is set back by a certain amount. At the beginning of the second operating mode, this alignment of the rotor is therefore effected firstly in an angular position which is slightly before the angular position, in which the rotor was located when the second operating mode was last brought out of operation. By way of this, it is ensured that the coupling at all events engages given a further rotation and that valve element is co-moved in the desired manner.

Starting from the described initial position, the rotor is then rotated into exactly the desired new angular position by the control device by way of a suitable subjection of the stator coils to current in the manner described above. This is preferably effected in a time-controlled manner, by way of the stator being subjected to current at a predefined frequency for a time interval which is set by the control device, wherein the frequency preferably moves in the very low range which is mentioned above. After reaching the desired angular position, the rotor is stopped and one changes back into the first operating mode, in which the rotor is preferably rotated in the opposite rotation direction, so that the coupling disengages and the valve element is held in the reached switching position in the described manner by way of the pressure reduction in the delivery chamber. The valve element can be precisely positioned by way of this method, so that the most varied of switching functions, such as switch-over functions, switching functions of a distribution (manifold) valve and/or setting of a mixing valve can be carried out.

The invention is hereinafter described by way of example and by way of the attached figures. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an exploded view of the centrifugal pump assembly according to a first embodiment of the invention;

FIG. 2 is a perspective view of the centrifugal pump assembly according to FIG. 1 with a removed pump casing and valve element;

FIG. 3 is a perspective view of the motor shaft of the centrifugal pump assembly according to FIGS. 1 and 2 as well as of the coupling part of the valve element;

FIG. 4 is a sectioned view of the centrifugal pump assembly according to FIG. 1 with the valve element in a first position;

FIG. 5 is a sectioned view according to FIG. 4 with the valve element in a second position;

FIG. 6 is a plan view upon the opened pump casing of the centrifugal pump assembly according to FIGS. 1 to 3 with the valve element in a first switching position;

FIG. 7 is a view according to FIG. 6 with the valve element in a second switching position;

FIG. 8 is a view according to FIGS. 6 and 7 with the valve element in a third switching position;

FIG. 9 is a schematic view of the hydraulic construction of a heating facility with a centrifugal pump assembly according to FIGS. 1 to 8;

FIG. 10 is an exploded view of a centrifugal pump assembly according to a second embodiment of the invention;

FIG. 11 is a perspective view of the opened valve element of the centrifugal pump assembly according to FIG. 10;

FIG. 12 is a perspective view of the closed valve element according to FIG. 11;

FIG. 13 is a sectioned view of the centrifugal pump assembly according to FIG. 10 with the valve element in a first position;

FIG. 14 is a sectioned view according to FIG. 13 with the valve element in a second position;

FIG. 15 is a plan view upon the opened pump casing of the centrifugal pump assembly according to FIGS. 10 to 14 with the valve element in a first switching position;

FIG. 16 is a view according to FIG. 15 with the valve element in a second switching position;

FIG. 17 is a view according to FIGS. 15 and 16 with the valve element in a third switching position;

FIG. 18 is a view according to FIGS. 15 to 17 with the valve element in a fourth switching position; and

FIG. 19 is a schematic view of the hydraulic construction of a heating facility with a centrifugal pump assembly according to FIGS. 10 to 18.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings, the embodiment examples of the centrifugal pump assembly according to the invention which are described in the following description relate to applications in heating systems and/or air conditioning systems, in which a fluid heat transfer medium, in particular water is circulated by the centrifugal pump assembly.

The centrifugal pump assembly according to both embodiments of the invention comprises a motor casing 2, in which an electrical drive motor is arranged. This in the known manner comprises a stator 4 as well as a rotor 6 which is arranged on a rotor shaft 8. The rotor 6 rotates in a rotor space which is separated from the stator space, in which the stator 4 is arranged, by way of a can or a canned pot 10. This means that here it is the case of a wet-running electrical drive motor. The motor casing 2 is connected to a pump casing 12 at an axial end, in which pump casing an impeller 14 which is connected to the rotor shaft 8 in a rotationally fixed manner rotates.

An electronics casing 16 which contains control electronics or a control device 17 for the activation of the electrical drive motor in the pump casing 2 is arranged at the axial end of the motor casing 2 which is opposite to the pump casing 12. The electronics casing 16 could also be arranged at another side of the pump casing 2 in a corresponding manner.

A movable valve element 18 is moreover arranged in the pump casing 12. This valve element 18 is rotatably mounted on a pivot 20 in the inside of the pump casing 12, and specifically such that the rotation axis of the valve element 18 is aligned with the rotation axis X of the impeller 14. The pivot 20 is fixed to the base of the pump casing 12 in a rotationally fixed manner. The valve element 18 is not only rotatable about the pivot 20 but is movable in the longitudinal direction X by a certain amount. This linear movability is limited in one direction by way of the pump casing 12, upon which the valve element 18 butts with its outer periphery.

In the pump casing 12, the valve element 18 separates a suction chamber 24 from a delivery chamber 26. The impeller 14 rotates in the delivery chamber 26. The delivery chamber 26 is connected to the delivery branch 27 of the centrifugal pump assembly which forms the outlet of the centrifugal pump assembly.

With regard to both represented embodiments, a mechanical coupling is likewise provided between the drive motor and the valve element, wherein concerning these embodiments, the drive motor can be activated in two different operational types or modes by way of the control device 17. In a first operating mode which corresponds to the normal operation of the circulation pump assembly, the drive motor rotates in the conventional manner at a desired speed which can be adjusted, in particular by the control device 17. In the second operating mode, the drive motor is activated (controlled) in open loop operation, so that the rotor can be rotated stepwise in individual angular steps which are smaller than 360 and which are set by the control device 17. The drive motor can therefore be moved in individual steps in the manner of a stepper motor, which concerning these embodiment examples is used in order to move the valve element in small angular steps into a defined position in a targeted manner, as is described hereinafter.

With regard to the first embodiment according to FIGS. 1 to 9, a mixing valve as can be used for example for temperature adjustment for a floor heating is integrated in the pump casing 2.

The motor casing 2 with the electronics casing 16 corresponds to the previously described embodiment. The pump casing 12, apart from the delivery branch 27 (delivery branch connection or simply delivery connection), comprises two suction-side branches 32 and 34 which run out into inlets 28 and 30 on the base of the pump casing 12, said inlets being situated in a plane transverse to the rotation axis (X).

The valve element 18 is configured in a drum-like manner and consists of a pot-like lower part 76 which at its side which faces the impeller 14 is closed by a cover 78. A suction opening 36 is formed in the central region of the cover 78. The suction opening 36 is engaged with the suction port 38 of the impeller 14. The valve element 18 is rotatably mounted on a pivot 20 which is arranged in the base of the pump casing 12. Here, the rotation axis of the valve element 18 corresponds to the rotation axis X of the rotor shaft 8. The valve element 18 is likewise axially displaceable along the axis X and is pressed by a spring 48 into the idle position which is shown in FIG. 5 and in which the valve element 18 is located in released position, in which the lower part 76 does not bear on the base of the pump casing 12, so that the valve element 18 is essentially freely rotatable about the pivot 20. In the released position, the face end of the rotor shaft 8 which is configured as a coupling 108 functions as an axial stop. The coupling 108 engages with a counter coupling 110 which is arranged on the valve element 18 in a rotationally fixed manner. The coupling 108 comprises inclined (beveled) coupling surfaces which along a peripheral line essentially describe a saw-toothed profile in a manner such that a torque transmission from the coupling 108 onto the counter coupling 110 is only possible in one rotation direction, specifically in the rotation direction A in FIG. 3. In contrast, the coupling slips through in the opposite rotation direction B, wherein an axial movement of the valve element 18 occurs. The rotation direction B is that rotation direction, in which the pump assembly is driven in normal operation. In contrast, the rotation direction A is used for the targeted actuation of the valve element 18. This means that a rotation-direction-dependent coupling is formed here. However, the counter-coupling 110 additionally disengages from the coupling 108 due to the pressure in the delivery chamber 26. If the pressure in the delivery chamber 26 increases, then a pressing force which is opposed to the spring force of the spring 48 and which exceeds this acts upon the cover 78, so that the valve element 18 is pressed into the bearing position as is shown in FIG. 4. In this position, the lower part 76 bears on the base side of the pump casing 12, so that on the one hand the valve element 18 is non-positively held and on the other hand a sealed bearing contact is achieved, said contact sealing the delivery side and the suction side with respect to one another in the subsequently described manner.

The suction branch 32 runs out at an inlet 28 and the suction branch 34 at an inlet 30, in the base of the pump casing 12 into the interior of this, which is to say into the suction chamber 24. The lower part 76 of the valve element 18 in its base comprises an arched opening 112 which extends essentially over 90. FIG. 6 shows a first switching position, in which the opening 112 only overlaps the inlet 30, so that a flow path is only given from the suction branch 34 to the suction opening 36 and therefore to the suction port 38 of the impeller 14. The second inlet 28 is sealingly closed by the base of the valve element 18 which bears in the peripheral region of this second inlet. FIG. 8 shows the second switching position, in which the opening 112 only overlaps the inlet 28, whilst the inlet 30 is closed. In this switching position, only a flow path from the suction branch 32 to the suction port 38 is opened. FIG. 7 now shows an intermediate position, in which the opening 112 overlaps both inlets 28 and 30, wherein the inlet 30 is only partly released. A mixing ratio between the flows from the inlets 28 and 30 can be changed by way of changing the degree of release of the branch 30. The valve element 18 can also be actuated or adjusted in small steps via the stepwise actuation of the rotor shaft 8, in order to change the mixing ratio.

Such a functionality can be applied for example in a hydraulic system as is shown in FIG. 9. There, the centrifugal pump assembly with the integrated valve as has been described above is characterized by the dashed line 1. The hydraulic circuit comprises a heat source 114 in the form of a gas heating boiler for example, the outlet of which running out for example into the suction branch 34 of the pump casing 12. In this example, a floor heating circuit 116 whose return is connected to the inlet of the heat source 114 as well as to the suction branch 32 of the centrifugal pump assembly 114 connects onto the delivery branch 27 of the centrifugal pump assembly 1. A further heating circuit 120 can be supplied with a heat transfer medium which has the outlet-side temperature of the heat source 114, via a second centrifugal pump assembly 118. The floor heating circuit 116 in contrast can be regulated in its feed temperature in a manner such that cold water from the return is admixed to the hot water at the outlet side of the heat source 114, wherein the mixing ratio can be changed by way of changing the opening ratios of the inlets 28 and 30 in the manner described above by way of rotating the valve element 18.

The second embodiment example according to FIGS. 10 to 19 shows a centrifugal pump assembly which additionally to the previously described mixing function yet comprises a switch-over functionality for the additional supply of a secondary heat exchanger for the heating of service water.

Concerning this embodiment, the mounting and drive of the valve element 18 i is effected just as with the ninth embodiment. In contrast to the valve element 18, the valve element 18 i additionally to the opening 112 comprises a through-channel 122 which extends from an opening 124 in the cover 78 i to an opening in the base of the lower part 76 i and therefore connects the two axial ends of the valve element 18 i to one another. An arched bridging opening 126 is moreover yet formed in the valve element 18 i and this opening is closed to the delivery chamber 28 by the cover 78 i and is only open to the lower side, which is to say to the base of the lower part 76 i and thus to the suction chamber 24.

Apart from the delivery branch 27 and both previously described suction branches 34 and 32, the pump casing 12 comprises a further branch 128. The branch 128 runs out in an inlet 130 in the base of the centrifugal pump assembly 12 additionally to the inlets 28 and 30, into the suction chamber 24. The various switching positions are explained by way of FIGS. 15 to 18, wherein the cover 78 i of the valve element 18 i is shown in a partly opened manner in these figures, in order to clarify the position of the openings which lie therebelow. FIG. 15 shows a first switching position, in which the opening 112 lies opposite the inlet 30, so that a flow connection from the suction branch 34 to the suction port 38 of the impeller 14 is created. In the switching position according to FIG. 16, the opening 112 lies over the inlet 130, so that a flow connection from the branch 128 to the suction opening 36 and via this into the suction port 38 of the impeller 14 is created. In a further switching position which is shown in FIG. 17, the opening 112 lies over the inlet 30, so that again a flow connection from the suction branch 34 to the suction port 38 of the impeller 14 is given. A partial overlapping of the opening 124 and of the through-hole 122 with the inlet 28 simultaneously takes place, so that a connection between the delivery chamber 26 and the suction port 32 which functions here as a delivery branch is created. The bridging opening 126 simultaneously overlaps the inlet 130 and a part of the inlet 28, so that a connection from the branch 128 to the branch 32 is likewise created via the inlet 130, the bridging opening 126 and the inlet 28.

FIG. 18 shows a fourth switching position, in which the through-channel 122 completely overlaps the inlet 28, so that the branch 32 is connected to the delivery chamber 26 via the through-channel 122 and the opening 124. Simultaneously, the bridging opening 126 continues to cover only the inlet 130. The opening 112 continues to cover the inlet 30.

Such a centrifugal pump assembly can be applied for example in a heating system as is shown in FIG. 19. Here, the dashed line delimits the centrifugal pump assembly 1, as has just been described by way of FIGS. 10 to 18. The heating system again comprises a primary heat exchanger or a heat source 114 which for example can be gas heating boiler. At the outlet side, the flow path runs into a first heating circuit 120 which can be formed for example by way of conventional radiators. A flow path simultaneously branches to a secondary heat exchanger 56 for heating service water. The heating system moreover comprises a floor heating circuit 116. The returns of the heating circuit 120 and of the floor heating circuit 116 run out into the suction branch 34 on the pump casing 12. The return from the secondary heat exchanger 56 runs out into the branch 128 which provides two functionalities as is described hereinafter. The branch 32 of the pump casing 12 is connected to the feed of the floor heating circuit 116.

When the valve element 18 i is located in the first switching position represented in FIG. 15, the impeller 14 delivers fluid from the suction branch 34 via the delivery branch 27 through the heat source 140 and the heating circuit 120 and back to the suction branch 34. If the valve element 18 i is located in the second switching position which is shown in FIG. 16, the facility is switched over to service water operation and in this condition the pump assembly or the impeller 14 delivers fluid from the branch 128 which serves as a suction branch, through the delivery branch 27, via the heat source 114 through the secondary heat exchanger 56 and back to the branch 128. The floor heating circuit 116 is additionally supplied if the valve element 18 i is located in the third switching position which is shown in FIG. 17. The water flows into the suction port 38 of the impeller 14 via the suction branch 34 and is delivered via the delivery branch 27 through the first heating circuit 120 via the heat source 114 in the described manner. The fluid at the outlet side of the impeller 14 simultaneously exits the delivery chamber 26 into the opening 124 and through the through-channel 122 and thus flows to the branch 32 and via this into the floor heating circuit 116.

Fluid simultaneously flows via the bridging opening 126 into the branch 32 via the branch 128 and the inlet 130, in the switching position which is shown in FIG. 17. This means that here water flows via the heat source 114 through the secondary heat exchanger 26 and the branch 128 to the branch 32. Since essentially no heat is taken at the secondary heat exchanger 56 in this heating operation, hot water is admixed to the branch 32 additionally to the cold water which flows out of the delivery chamber 26 to the branch 32 via the through-channel 122. The quantity of the admixed warm water at the branch 32 can be varied by way of changing the degree of opening via the valve position 18 i. FIG. 18 shows a switching position, in which the admixing is switched off and the branch 32 is exclusively in direct connection with the delivery chamber 26. In this condition, the water in the floor heating circuit 116 is delivered in the circuit without any supply of heat. It is to be recognized that with this embodiment, a switching between the heating and service water heating as well as simultaneously the supply of heating circuits with two different temperatures, specifically of a first heating circuit 120 with the exit temperature of the heat source 114 and of a floor heating circuit 116 with a temperature which is reduced via a mixing function, can also be achieved by way of the change of the switching positions of the valve element 18 i.

The problem of bringing the rotor 6 and the valve element 18, 18 i again into a defined alignment with respect to their angular positions arises on changing into the second operating mode which demands a reversal of the rotation direction. This is due to the fact that the coupling 108 and the counter coupling 110 are disengaged in the first operating mode in normal operation of the circulation pump assembly when the impeller 14 delivers fluid. The valve element 18, 18 i should essentially be held essentially in the position, in which it was when the pump assembly changed the last time from the second operating mode into the first operating mode by way of the control device 17. The position of the rotor 6 is simultaneously known to the control device 17 and the control device 17 is configured such that it stores the rotor position. However, since the valve element 18, 18 i having possibly been displaced by a certain amount cannot be completely ruled out, with a renewed changing into the second operating mode, a positioning of the rotor 6 is preferably firstly carried out in a manner such that by way of a suitable activation of the stator 4, the control device 17 does not rotate the rotor 6 completely into the stored angular position, but preferably stops it shortly before. I.e. in a first step, on starting operation of the second operating mode, the rotor 6 is rotated into a previously stored angular position or into an angular position which in the rotation direction lies slightly before the lastly stored angular position. The rotor together with the valve element 18, 18 i can subsequently be rotated into a desired second angular position, wherein the control device 17 activates the stator 6 such that the rotor 6 in this second operating mode rotates precisely about the desired angle. With this rotation, the counter-coupling 110 is caught or driven via the coupling 108, so that the valve element 18, 18 i is then rotated into the desired angular position. The rotor 6 is stopped at this angular position and the control device 17 switches back into the first operating mode or into the first operating type again and starts the rotor 6 in the opposite rotation direction, so that the coupling 108 can disengage from the counter coupling 110 and furthermore the coupling 108 and the counter coupling 110 can completely disengage due to the axial displacement of the valve element 18, 18 i by way of the pressure which is produced in the delivery chamber 26, and the valve element 18, 18 i can be held in the reached switching position by way of the bearing contact on the base of the pump casing 12.

The coupling 108 comprises two inclinations or wedge surfaces 132 which extend in a manner departing from two face edges 134 which run essentially in the diametrical direction with respect to the rotation axis X. Engagement surfaces 136 which run essentially in a plane which is spanned by the rotation axis X and a diameter line to this rotation axis X extend at the side of the face edges 134 which is away from the wedge surfaces 132. The counter coupling 110 comprises a web-like projection 138 which extends in the diameter direction with respect to the rotation axis X, projects in the axial direction and comprises two essentially parallel side surfaces which again extend in a plane which is essentially spanned by the diameter line and the rotation axis X or axes which are parallel to these. The side surfaces of the projection 138 come to bear on the engagement surfaces 136 when the coupling is engaged. In the opposite rotation direction D, the projection 138 slides on the wedge surfaces 137 amid axial displacement. With this embodiment of the coupling 108 and of the counter coupling 110 there are exactly two positions which are offset to one another by 180°, in which the rotor 6 and the valve element 18, 18 i can be coupled to one another.

The pump casing 12 is configured of one part in the previously described embodiment examples. However, it is to be understood that the pump casing can also be configured of several parts. In particular, a valve casing, in which the described valve element is arranged, can be provided separately from the pump casing, whilst only the impeller is arranged in the pump casing. Such a valve casing and pump casing can be connected to one another in a suitable manner.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 

1. A pump assembly comprising: an electrical drive motor; at least one impeller which is rotatingly driven by the electrical drive motor; and a control device which activates the drive motor, wherein the control device is configured to selectively activate the drive motor in at least one first operating mode or in a second operating mode, wherein in the first operating mode, the drive motor is activated by the control device such that a rotor of the drive motor continuously rotates for producing a flow and a pressure at the impeller, and in the second operating mode, the drive motor is controlled by the control device such that the rotor of the drive motor is moved further stepwise in at least one selected angular step for reaching a certain angular position.
 2. A pump assembly according to claim 1, wherein the control device is configured such that the drive motor rotates at higher angular speed in the first operating mode than in the second operating mode.
 3. A pump assembly according to claim 1, wherein the control device is configured such that in the first operating mode, the drive motor in is speed adjustable and closed-loop controllable.
 4. A pump assembly according to claim 1, wherein the control device is configured such that in the second operating mode, the drive motor is controlled by the control device with an open-loop.
 5. A pump assembly according to claim 1, wherein the control device is configured such that in the second operating mode, the drive motor is activated by the control device at a frequency <10 Hertz and/or the motor current corresponds to twice to fourfold the rated amperage, for which the drive motor is designed.
 6. A pump assembly according to claim 1, wherein the control device comprises a frequency converter.
 7. A pump assembly according to claim 1, wherein the control device is configured such that a number and/or a size of the individual angular steps, in which the rotor is moved in the second operating mode, is selectable.
 8. A pump assembly according to claim 1, wherein the control device is configured such that the control device activates the drive motor such that a drive motor rotation direction in the second operating mode is opposite to a drive motor rotation direction in the first operating mode.
 9. A pump assembly according to claim 1, wherein the rotor of the drive motor, in addition to being coupled to the at least one impeller, is coupled to at least one further movable component via a releasable coupling.
 10. A pump assembly according to claim 9, wherein the releasable coupling is rotation-direction dependently releasable such that in a first rotation direction the releasable coupling is engaged and in the opposite second rotation direction the releasable coupling is released.
 11. A pump assembly according to claim 9, wherein the releasable coupling is formed at a face end of a rotor shaft of the rotor and has a saw-tooth profile.
 12. A pump assembly according to claim 9, wherein the at least one further movable component is a valve element part of a mixing valve and/or switch-over valve.
 13. A pump assembly according to claim 12, wherein: the valve element is configured and arranged such that the valve element is rotatingly movable between at least two switching positions; and a rotation axis of the valve element is arranged aligned to a rotation of the drive motor.
 14. A pump assembly according to claim 12, wherein the valve element is arranged in the pump assembly such that the valve element comprises a pressure surface, upon which a pressure prevailing at the outlet side of the at least one impeller acts, and the valve element is movably mounted in a direction transverse to the pressure surface between a bearing position, in which the valve element bears on at least one contact surface, and a released position, in which the valve element is released or distanced to the contact surface, wherein a restoring element is provided, said restoring element producing a restoring force which is directed oppositely to the pressing force which is produced by the pressure on the pressure surface.
 15. A pump assembly according to claim 14, wherein the contact surface is a sealing surface.
 16. A pump assembly according to claim 14, wherein a movement path between the bearing position and a released position is different to a movement path between the at least two switching positions of the valve element.
 17. A pump assembly according to claim 1, wherein the pump assembly is configured as a circulation pump assembly. 